The invention relates to a lubricator pump for effecting automatic or semi-automatic lubrication of various types of fabricating equipment, as for example, punches, dies and the like, eliminating manual swabbing and like operations as well as reducing lubricant consumption as the quantity of lubricant employed may be accurately adjusted to that necessary to achieve the desired results without the supply of excessive lubricant. In general, such type of pump structures employ a reciprocal piston or plunger, the stroke of which may be adjusted to the desired output requirements and it has been found that rotatable cam members form very simple yet efficient elements for driving the plunger, with the latter usually being returned to its initial position by suitable biasing means such as compression springs.
In many instances the plunger is operatively connected to the cam by a cam follower or rocker arm which is pivotally supported on an axis extending parallel to the cam shaft and is interposed between the cam and the adjacent end of the plunger to operatively connect the same. A typical example of such type of lubricator is illustrated in U.S. Letters Pat. No. 3,139,156, granted on June 30, 1974 to R.F. Urso. Follower arms of this type are employed in pump structures such as here involved for two purposes, the first being to reduce lateral thrust on the plunger which would otherwise exist if the plunger were seated directly on the cam, i.e. the follower arm providing a considerable reduction in lateral forces as it tends to transmit the cam movement more directly along the axis of the plunger. Second, the following arm may be so proportioned that the plunger may be actuated independently of the cam by suitable movement of the rocker arm, for example by a manual operation.
The factors relating to side thrust are of importance in the design of lubricator pumps as relatively very high pressures may be involved with respect to the discharge of the lubricant, pressures as high as 6000 psi not being uncommon. Consequently, lateral forces, which may be comparatively high, increase frictional loads both in the plunger and in the cam connections, and in addition may undesirably stress other elements of the structure as for example, pivot supports, cams and cam shafts, as well as the bearings for the latter.
As lubricator devices of this type may be designed to lubricate a plurality of points, for example, from 2 to 24, or more, a like number of pumps will be required, which are driven through respective cams, normally carried by a common cam shaft. In view of the possibly high pressures required, it becomes desirable to operate the individual pumps of an assembly sequentially, with the respective cams thus preferably being staggered as to their operating cycles, i.e. the high-low configuration of the cams are circumferentially staggered whereby full plunger actuation in pumping direction of the respective plungers will be distributed around one rotation of the cam shaft. However, where a plurality of pumping units are employed, particularly a large number, the individual plungers will be at various stages of an operational cycle whereby one plunger may be at the end of its pumping stroke, another at the end of its return stroke and the remaining plungers at various stages intermediate these two.
It will be readily appreciated that under such circumstances the production of relatively large lateral forces, particularly with respect to forces acting on the cam shaft, the latter may be subjected to forces acting in a plurality of different directions. In such event, undesirable flexing may take place in the shaft, i.e., a so-called rubber-banding effect, which in turn can impose severe stresses on the cam shaft bearings. The present invention therefore is directed to a reduction if not substantial elimination of these undesirable conditions.
It is quite common in pump structures such as here involved to employ suitable means for permitting a visual determination of the lubricating operation whereby the operator can visually ascertain the amount of lubricant that is being consumed. (Note sight feed of the patent referred to.) In the devices of this type a suitable sight feed chamber is provided in which the lubricant may pass, usually drop by drop, either downwardly from an inverted discharge tube or upwardly through a suitable clear sight fluid or the like. Where a sight-fluid is employed the lubricant is forced upwardly through the sight fluid, which has a specific gravity greater than that of the lubricant and thus remains in operating position, or in the event of the use of a drip tube, the lubricant is drawn to the pump cylinder, under the pump action during the return stroke of the plunger, whereby the sight chamber is under a partial vacuum. All of the various pumps employ suitable valve means, normally of ball-type, to control the admission of lubricant into the pump cylinder and discharge therefrom. This is also true of pumps employing a drip tube and a sight chamber under partial vacuum. Thus, valve means is normally disposed adjacent the inlet for lubricant into the pump cylinder with such valve opening on an intake or return stroke and closing on a pressure or discharge stroke. In like manner valve means is disposed between the pump cylinder and the discharge port of the pump, which will be closed during an intake or return stroke of the plunger, but open during a pressure or discharge stroke to permit the discharge of lubricant from the pump. It will be appreciated that in this construction, where a drip tube and sight chamber are employed, the intake stroke of the plunger must create a sufficient vacuum in the sight chamber and in the lubricant supply line thereto a draw lubricant to the sight chamber, this normally entailing elevating the lubricant from a reservoir, disposed below the pump structure, upwardly into and through the drip tube, from which it may drop into a well formed by the sight chamber and ultimately be received in the cylinder.
In some cases the plunger and cylinder structure simultaneously forms the valving means for controlling the entry of lubricant into the cylinder, the cylinder being so designed that the plunger is completely withdrawn therefrom during its return stroke, thus opening the cylinder to the lubricant supply and when the plunger re-enters the cylinder during its pressure stroke it automatically closes the cylinder to the lubricant supply.
In either case the supply line to the sight chamber as well as the sight chamber itself will normally have a partial vacuum therein, due in part to the height of the lubricant column extending from the reservoir up to the sight chamber, which must be continuously maintained. Any increase in the pressure within the sight glass, i.e., a loss in the vacuum, will result in some reverse flow in the supply line to the sight feed chamber which will thus affect the amount of lubricant entering the sight chamber on the next intake stroke or strokes. The invention therefore has among its objects, in addition to the improvement in the pump drive arrangement, the novel disposition of valve means in the lubricant supply line to the sight chamber whereby the vacuum produced by the column of lubricant therein is not transmitted to the sight chamber.